Display device and method for manufacturing the same

ABSTRACT

A display device includes a first organic insulating layer covering video signal lines; a first metal layer provided above the first organic insulating layer; a first conductive layer provided above the first organic insulating layer and connected to a switching element via a first contact hole; a first inorganic insulating layer covering the first conductive layer and the first metal layer; a second conductive layer provided above the first inorganic insulating layer and connected to the first metal layer; a second inorganic insulating layer provided above the second conductive layer; a third conductive layer provided above the second inorganic insulating layer and connected to the first conductive layer via a second contact hole; and a fourth conductive layer provided above the second inorganic insulating layer, connected to the first metal layers via a third contact hole, and connected to the second conductive layer via a fourth contact hole.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2016-181726, filed on Sep. 16,2016, the entire contents of which are incorporated herein by reference.

FIELD

The present invention relates to a display device including a touchsensor and a method for manufacturing the same.

BACKGROUND

In electronic devices such as mobile computers, personal computers, andcar navigation systems, touch panels which allow data to be inputted bydetecting a touch position of contact with a fingertip, a pen point, orthe like while an image on a display screen of a liquid crystal displaydevice or the like is being viewed have recently become widely used.

For example, Japanese Unexamined Patent Application Publication No.2015-122057 discloses a display device including: a lower substrate; agate line formed over the lower substrate so as to extend in a seconddirection (transverse direction); a gate insulating layer formed overthe gate line; a data line formed over the gate insulating layer so asto extend in a first direction (longitudinal direction); a firstprotective layer formed over the data line; a pixel electrode and asignal line formed over the first protective layer in each pixel area; asecond protective layer formed over the pixel electrode and the signalline; one electrode formed over the second protective layer so as toserve as a common electrode and a touch electrode; a liquid crystallayer formed over the electrode; and an upper substrate formed over theliquid crystal layer and provided with a black matrix, a color filter,and the like.

Further, for example, Japanese Unexamined Patent Application PublicationNo. 2009-058913 discloses a liquid crystal display device including: aliquid crystal display panel including a first substrate, a secondsubstrate, and liquid crystals sandwiched between the first substrateand the second substrate, the liquid crystal display panel including aplurality of pixels arranged in a matrix. In the display device, thefirst substrate has a laminated structure of a first transparentelectrode, a first insulating film, a second transparent electrode, asecond insulating film, and a third transparent electrode in atransparent display area provided in at least part of each of thepixels, the first transparent electrode, the first insulating film, thesecond transparent electrode, the second insulating film, and the thirdtransparent electrode being laminated in descending order of proximityto the first substrate, the first transparent electrode and the secondtransparent electrode are electrically insulated from each other andform a first retention capacitor via the first insulating film, and thesecond transparent electrode and the third transparent electrode areelectrically insulated from each other and form a second retentioncapacitor via the second insulating film.

SUMMARY

A display device according to an embodiment of the present inventionincludes: a plurality of video signal lines that supply video signals toa plurality of pixels; a first organic insulating layer covering theplurality of video signal lines; a first metal layer provided above thefirst organic insulating layer so as to extend along any of theplurality of video signal lines; a first conductive layer provided abovethe first organic insulating layer in each of the plurality of pixelsand connected to a switching element of the pixel via a first contacthole; a first inorganic insulating layer covering the first conductivelayer and the first metal layer; a second conductive layer providedabove the first inorganic insulating layer in each of a plurality ofpixel groups and electrically connected to the first metal layer; asecond inorganic insulating layer provided above the second conductivelayer; a third conductive layer provided above the second inorganicinsulating layer in each of the plurality of pixels and connected to thefirst conductive layer via a second contact hole; and a fourthconductive layer provided above the second inorganic insulating layer ineach of the plurality of pixel groups, connected to any of a pluralityof the first metal layers via a third contact hole, and connected to thesecond conductive layer via a fourth contact hole.

A method for manufacturing a display device according to an embodimentof the present invention includes: forming a plurality of video signallines that supply video signals to a plurality of pixels; forming afirst organic insulating layer that covers the plurality of video signallines; forming, in each of the plurality of pixels, a first contact holethat reaches a switching element of the pixel; forming, above the firstorganic insulating layer, a first metal layer that extends along any ofthe plurality of video signal lines; forming, above the first organicinsulating layer in each of the plurality of pixels, a first conductivelayer that is connected to a switching element of the pixel via thefirst contact hole; forming a first inorganic insulating layer thatcoves the first metal layer and the first conductive layer; forming asecond conductive layer above the first inorganic insulating layer ineach of a plurality of pixel groups; forming, above the secondconductive layer, a second inorganic insulating layer that covers theplurality of pixels; forming, in each of the plurality of pixels, asecond contact hole that reaches the first conductive layer and a thirdcontact hole that reaches the first metal layer; forming a fourthcontact hole that reaches the second conductive layer; forming, abovethe second inorganic insulating layer in each of the plurality ofpixels, a third conductive layer that is connected to the firstconductive layer via the second contact hole; and forming, above thesecond inorganic insulating layer in each of the plurality of pixelgroups, a fourth conductive layer that is connected to the first metallayer via the third contact hole and connected to the second conductivelayer via the fourth contact hole.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating a schematic configuration of adisplay device according to an embodiment of the present invention;

FIG. 2 is a circuit diagram illustrating a circuit configuration of adisplay device according to an embodiment of the present invention thatis involved in a display;

FIG. 3 is a circuit diagram illustrating a circuit configuration of adisplay device according to an embodiment of the present invention thatis involved in touch detection;

FIG. 4 is a circuit diagram illustrating a circuit configuration of onepixel group of a display device according to an embodiment of thepresent invention that is involved in a display;

FIG. 5 is a circuit diagram illustrating a circuit configuration of onepixel group of a display device according to an embodiment of thepresent invention that is involved in touch detection;

FIG. 6 is a plan view illustrating a configuration of a pixel of adisplay device according to an embodiment of the present invention;

FIG. 7 is a cross-sectional view illustrating a configuration of a pixelof a display device according to an embodiment of the present invention;

FIG. 8 is a cross-sectional view illustrating a configuration of a pixelof a display device according to an embodiment of the present invention;

FIG. 9 is an enlarged cross-sectional view illustrating a configurationof a pixel of a display device according to an embodiment of the presentinvention;

FIG. 10 is an enlarged cross-sectional view illustrating a configurationof a pixel of a display device according to an embodiment of the presentinvention;

FIG. 11 is an enlarged cross-sectional view illustrating a configurationof a pixel of a display device according to an embodiment of the presentinvention;

FIG. 12A is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 12B is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 13A is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 13B is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 14A is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 14B is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 15A is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 15B is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 16A is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 16B is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 17A is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 17B is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 18A is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 18B is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 19A is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 19B is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 20A is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 20B is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention;

FIG. 21A is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention; and

FIG. 21B is a cross-sectional view illustrating a method formanufacturing a pixel of a display device according to an embodiment ofthe present invention.

DESCRIPTION OF EMBODIMENTS

A configuration of a display device according to an embodiment of thepresent invention and a method for manufacturing the same are describedin detail below with reference to the drawings. It should be noted thata display device of the present invention is not limited to theembodiment described below but may be implemented in variousmodifications. Further, for convenience of explanation, the dimensionalratios of the drawings may be different from actual ratios, and some ofthe components may be omitted from the drawings.

In manufacturing a so-called in-cell type touch panel integrally formedwith a liquid crystal display device and a touch sensor as in theinvention described in Japanese Unexamined Patent ApplicationPublication No. 2015-122057, for example, there is a problem that amanufacturing process becomes complicated; for example, a step offorming a contact hole for connecting the signal line and one electrodeserving as a common electrode and a touch electrode, is separatelyrequired.

However, in Japanese Unexamined Patent Application Publication No.2015-122057, a configuration for connecting signal lines formed in thesame layer as a pixel electrode and one electrode serving as a commonelectrode and a touch electrode, and a manufacturing method thereof arenot disclosed.

In addition, in the invention described in Japanese Unexamined PatentApplication Publication No. 2009-058913, in order to solve the problemof constituting a storage capacitor having a sufficient size in adisplay device having a liquid crystal display panel with miniaturizedpixel, the display provide no touch sensors.

It is therefore an object of the present invention to provide aconfiguration capable of suppressing an increase in the number of masksfor manufacturing thereof and suppressing an increase inphotolithography steps and a manufacturing method thereof in a displaydevice having a touch sensor.

<First Embodiment>

The following describes a schematic configuration of a display device100 according to the present embodiment, a circuit configuration of thedisplay device 100, a configuration of a pixel of the display device100, and a method for manufacturing the display device 100.

[Schematic Configuration]

FIG. 1 is a perspective view illustrating a schematic configuration of adisplay device 100 according to the present embodiment. The displaydevice 100 according to the present embodiment includes an arraysubstrate 102, a counter substrate 106, and a plurality of connectionterminals 112.

The array substrate 102 includes at least a first substrate 104 and aplurality of pixels 110. The first substrate 104 has a display area 104a and a terminal area 104 b on a surface thereof. The first substrate104 serves as a support for the plurality of pixels 110. The firstsubstrate 104 can be made of a material such as a glass substrate, anacrylic resin substrate, an alumina substrate, or a polyimide substrate.

The plurality of pixels 110 are arranged on one surface of the firstsubstrate 104. The display area 104 a is an area where the plurality ofpixels 110, which contribute to an image display, are arranged. In thepresent embodiment, the plurality of pixels 110 are arranged in rows andcolumns. The plurality of pixels 110 may be arranged in any number. Forexample, the plurality of pixels 110 may be arranged in a matrix with mrows and n columns (where m and n are integers). It should be notedthat, instead of being arranged in rows and columns, the plurality ofpixels 110 may be appropriately arranged in any other arrangement suchas a delta arrangement or a PenTile arrangement.

The counter substrate 106 includes a second substrate 108. The secondsubstrate 108 may be similar to the first substrate 104. The secondsubstrate 108 is provided on an upper surface of the display area 104 aso as to face the first substrate 104. The second substrate 108 is fixedto the first substrate 104 by a sealant 114 surrounding the display area104 a. The display area 104 a disposed on the first substrate 104 issealed with the second substrate 108 and the sealant 114.

It should be noted that although the display device 100 according to thepresent embodiment includes the aforementioned second substrate 108, thesecond substrate 108 is not limited to a plate-like member but may bereplaced by a film substrate or a sealing substrate coated with resin orthe like.

The counter substrate 106 may further include a color filter, alight-blocking layer, a polarizing plate, a phase plate, and the like,although these components are not illustrated. The color filter isdisposed in places facing each separate pixel 110. The light-blockinglayer (also called “black matrix”) is disposed in places demarcatingeach separate pixel 110. The polarizing plate and the phase plate coverthe plurality of pixels 110 and are disposed on an outer surface of thecounter substrate 106.

The plurality of connection terminals 112 are arranged at one end of thefirst substrate 104 and outside of the second substrate 108. Theterminal area 104 b is an area where the plurality of connectionterminals 112 are arranged. To the plurality of connection terminals112, a circuit board (not illustrated) is connected. The circuit boardconnects the display device 100 to a device that outputs video signals,a power source, and the like. The plurality of connection terminals 112have outwardly exposed contacts connected to the circuit board.

The foregoing has described a schematic configuration of the displaydevice 100 according to the present embodiment. The following describesa circuit configuration of the display device 100 according to thepresent embodiment with reference to the drawings.

[Circuit Configuration]

FIG. 2 is a circuit diagram illustrating a circuit configuration of thedisplay device 100 according to the present embodiment that is involvedin a display. FIG. 3 is a circuit diagram illustrating a circuitconfiguration of the display device 100 according to the presentembodiment that is involved in touch detection.

The display device 100 according to the present embodiment includes aplurality of pixel circuits 120, a plurality of scanning signal lines122, a plurality of video signal lines 124, a plurality of touch signallines 127, a scanning line driving circuit 128, a video line drivingcircuit 130, and a touch scanning detection circuit 132.

Each of the plurality of pixel circuits 120 is provided for thecorresponding one of the plurality of pixels 110. The plurality of pixelcircuits 120 are arranged in rows and columns.

As illustrated in FIG. 2, each of the plurality of scanning signal lines122 extends in a horizontal direction and is connected to those of theplurality of pixel circuits 120 arranged in rows and columns which arearranged in the same pixel row.

As illustrated in FIG. 2, each of the plurality of video signal lines124 extends in a vertical direction and is connected to those of theplurality of pixel circuits 120 arranged in rows and columns which arearranged in the same pixel column.

As illustrated in FIG. 3, each of the plurality of touch signal lines127 extends in a vertical direction and is connected to any one of aplurality of touch detection electrodes 135. That is, the plurality oftouch signal lines 127 are provided in at least the same number as theplurality of touch detection electrodes 135. It should be noted thatalthough the present embodiment shows an aspect in which the pluralityof touch signal lines 127 extend in a vertical direction, they mayextend in a horizontal direction.

As illustrated in FIG. 2, the scanning line driving circuit 128 isconnected to the plurality of scanning signal lines 122. The scanningline driving circuit 128 selects pixel rows in sequence through theplurality of scanning signal lines 122.

As illustrated in FIG. 2, the video line driving circuit 130 isconnected to the plurality of video signal lines 124. As the scanningline driving circuit 128 selects pixel rows through the scanning signallines 122, the video line driving circuit 130 causes a voltagecorresponding to a video signal of the pixel row selected to be writtenthrough the plurality of video signal lines 124 to pixels electricallyconnected to the plurality of video signal lines 124.

FIG. 2 illustrates a common electrode 134 disposed for the plurality ofpixel circuits 120. The common electrode 134 is divided into commonelectrodes 134 for each separate pixel group. Thus, each of theplurality of common electrodes 134 thus divided is disposed across onepixel group. One pixel group is constituted by pixels 110 arranged in amatrix with m1 rows and n1 columns (where m1 and n1 are integers ofsmaller than m and n, respectively). The common electrodes 134 disposedacross each separate pixel group function as the touch detectionelectrodes 135 in a touch drive mode.

As illustrated in FIG. 3, the touch scanning detection circuit 132 isconnected to the plurality of touch signal lines 127. Each of theplurality of touch signal lines 127 is connected to any of the pluralityof touch detection electrodes 135. Each of the plurality of touchdetection electrodes 135 is provided across one pixel group. Each of theplurality of touch detection electrodes 135 needs only have such a sizeas to have necessary and sufficient resolving power in touch detection.For example, each of the plurality of touch detection electrodes 135needs only have a size of approximately 4 mm square to 5 mm square. Thenumber of pixels 110 that are arranged to constitute one pixel groupneeds only be determined in consideration of this size. The plurality oftouch detection electrodes 135 function as the aforementioned commonelectrodes 134 in a display mode. Further, the plurality of touch signallines 127 function as common potential lines 126 in the display mode.

The touch scanning detection circuit 132 detects the position of a touchby applying touch drive signals to the plurality of touch detectionelectrodes 135 in sequence during the touch drive mode and acquiringvariations in capacitance of the plurality of touch detection electrodes135.

FIG. 4 is a circuit diagram illustrating a circuit configuration of onepixel group 111 in the circuit diagram of FIG. 2 which illustrates thecircuit configuration involved in a display. FIG. 5 is a circuit diagramillustrating a circuit configuration of one pixel group 111 in thecircuit diagram of FIG. 3 which illustrates the circuit configurationinvolved in touch detection.

Each of the plurality of pixel groups 111 is constituted by a pluralityof pixel circuits 120. As mentioned above, in the present embodiment,each of the plurality of pixel groups 111 is constituted by a pluralityof pixel circuits 120 arranged in a matrix with m1 rows and n1 columns.As illustrated in FIG. 4, each of the plurality of pixel circuits 120includes a switching element 136, a liquid crystal capacitor 138, and aretention capacitor 140.

In the present embodiment, the switching element 136 is a thin-filmtransistor. The thin-film transistor has its gate connected to ascanning signal line 122. The thin-film transistor has its sourceconnected to a video signal line 124. The thin-film transistor has itsdrain connected a first end of the liquid crystal capacitor 138 and afirst end of the retention capacitor 140.

The liquid crystal capacitor 138 has its first end connected to thedrain of the thin-film transistor. The liquid crystal capacitor 138 hasits second end connected to a common potential line 126. Furthermore,specifically, the liquid crystal capacitor 138 has its second endconnected to the common potential line 126 via a common electrode 134.The common potential line 126 serves as a touch signal line 127 in thetouch drive mode. In one pixel group 111, the liquid crystal capacitors138 of pixel circuits 120 arranged in the same pixel row have theirsecond ends connected to the same common electrode 134.

The retention capacitor 140 has its first end connected to the drain ofthe thin-film transistor. The retention capacitor 140 has its second endconnected to a common potential line 126. Furthermore, specifically, theretention capacitor 140 has its second end connected to the commonpotential line 126 via a common electrode 134. In one pixel group 111,the retention capacitors 140 of pixel circuits 120 arranged in the samepixel row have their second ends connected to the same common electrode134.

As illustrated in FIG. 5, in one pixel group 111, the touch detectionelectrode 135 is disposed in the form of a plurality of strips. Each ofthe plurality of strip touch detection electrodes 135 is provided forpixels 110 arranged in a pixel row in one pixel group 111. The pluralityof strip touch detection electrodes 135 in one pixel group 111 areconnected to any one of the plurality of touch signal lines 127.

The foregoing has described a circuit configuration of the displaydevice 100 according to the present embodiment. The following describesin detail a configuration of a pixel 110 of the display device 100according to the present embodiment with reference to the drawings.

[Configuration of Pixel]

FIG. 6 is a plan view illustrating a configuration of a pixel 110 of thedisplay device 100 according to the present embodiment. FIG. 7 is across-sectional view illustrating the configuration of the pixel 110 ofthe display device 100 according to the present embodiment as takenalong line A1-A2 of FIG. 6. FIG. 8 is a cross-sectional viewillustrating the configuration of the pixel 110 of the display device100 according to the present embodiment as taken along line B1-B2 ofFIG. 6. FIG. 9 is a partially-enlarged cross-sectional view of part C inthe cross-sectional view of FIG. 7 which illustrates the configurationof the pixel 110. FIG. 10 is a partially-enlarged cross-sectional viewof part D in the cross-sectional view of FIG. 7 which illustrates theconfiguration of the pixel 110. FIG. 11 is a partially-enlargedcross-sectional view of part E in the cross-sectional view of FIG. 8which illustrates the configuration of the pixel 110.

The display device 100 according to the present embodiment includes thefirst substrate 104, the second substrate 108, the plurality ofswitching elements 136, the plurality of scanning signal lines 122, theplurality of video signal lines 124, a first organic insulating layer142, a first metal layer 144, a first conductive layer 150, a firstinorganic insulating layer 154, a second conductive layer 148, a secondinorganic insulating layer 156, a third conductive layer 146, a fourthconductive layer 152, and a liquid crystal layer 158.

The first substrate 104 serves as a support for the plurality of pixels110. The first substrate 104 can be made of a material such as a glasssubstrate, an acrylic resin substrate, an alumina substrate, or apolyimide substrate.

Each of the plurality of switching elements 136 is provided in thecorresponding one of the plurality of pixels 110. In the presentembodiment, the switching elements 136 are thin-film transistors.

The plurality of scanning signal lines 122 are provided for eachseparate horizontal arrangement (pixel row) of the plurality of pixels110. As illustrated in FIG. 6, each of the plurality of scanning signallines 122 is connected to the gate of a switching element 136 in onepixel 110. In the present embodiment, each of the plurality of scanningsignal lines 122 has a projecting part in one pixel 110, and theprojecting part functions as the gate of the switching element 136.

The plurality of video signal lines 124 are provided for each separatevertical arrangement (pixel column) of the plurality of pixels 110. Asillustrated in FIG. 6, each of the plurality of video signal lines 124is connected to the source of a switching element 136 in one pixel 110.In the present embodiment, each of the plurality of video signal lines124 has a projecting part in one pixel 110, and the projecting partfunctions as the source of the switching element 136. The plurality ofvideo signal lines 124 supply video signals to the plurality of pixels110.

The first organic insulating layer 142 covers the plurality of switchingelements 136, the plurality of scanning signal lines 122, and theplurality of video signal lines 124. The first organic insulating layer142 is provided with first contact holes 168. Each of the first contactholes 168 is a contact hole via which the drain of the switching element136 provided in the corresponding one of the plurality of pixels 110 andthe first conductive layer 150 are connected to each other.

The first organic insulating layer 142 can be made of a material such aspolyimide resin, acrylic resin, or a combination thereof.

The first metal layer 144 is a layer that functions as the commonpotential lines 126 in the display mode and functions as the touchsignal lines 127 in the touch drive mode. The first metal layer 144 isprovided above the first organic insulating layer 142. Furthermore, in aplan view, the first metal layer 144 is provided along any of theplurality of video signal lines 124. The first metal layer 144 needsonly be connected to the second conductive layer 148 provided in each ofthe plurality of pixel groups 111. Therefore, the required number oflines of the first metal layer 144 is not necessarily equal to thenumber of video signal lines 124. Therefore, the first metal layer 144does not need to be provided above one or some of the plurality of videosignal lines 124. It should be noted that, from the point of view ofviewability of the display device 100, each of the plurality of videosignal lines 124 may be provided with a first metal layer 144 serving asa dummy.

The first metal layer 144 can be made of a material such as alight-blocking metal having a laminated structure in which a W layer, aMoW layer, and an Al layer are sandwiched between upper and lower Molayers, a laminated structure in which an Al layer is sandwiched betweenupper and lower Ti layers, or the like.

The first conductive layer 150 is a layer that functions as firstelectrodes of the retention capacitors 140 in the display mode. Thefirst conductive layer 150 is provided above the first organicinsulating layer 142 in each of the plurality of pixels 110.Furthermore, the first conductive layer 150 is connected to the sourceor drain of the switching element 136 of the pixel 110 via the firstcontact hole 168. FIG. 7 illustrates an example in which the firstconductive layer 150 is connected to the drain of the switching element136.

The first conductive layer 150 can be made of a transparent conductivematerial such as ITO (indium tin oxide) or IZO (indium zinc oxide) or ofany combination thereof. Alternatively, the first conductive layer 150may be made of a light-blocking metal material other than ITO (indiumtin oxide) and IZO (indium zinc oxide). In this case, it is desirablethat the light-blocking metal material be the same as that of which thefirst metal layer 144 is made and be processed through the same steps asthat of which the first metal layer 144 is made. Further, in the presentembodiment, the first conductive layer 150 is larger in pattern shapethan the third conductive layer 146 described below.

The first inorganic insulating layer 154 is a layer that functions asdielectric layers of the retention capacitors 140. The first inorganicinsulating layer 154 covers the first conductive layer 150 and the firstmetal layer 144. The first inorganic insulating layer 154 can be made ofa material such as silicon oxide, silicon nitride, or a combinationthereof.

The second conductive layer 148 is a layer that functions as the touchdetection electrodes 135 in a touch detection mode. Further, the secondconductive layer 148 is a layer that functions as the common electrodes134 and second electrodes of the retention capacitors 140 in the displaymode. The second conductive layer 148 is provided above the firstinorganic insulating layer 154 in each of the plurality of pixel groups111. The second conductive layer 148 has a slit extending along a spacebetween adjacent pixel groups 111. Furthermore, in the presentembodiment, the second conductive layer 148 is disposed in the form of aplurality of islands in each separate pixel group 111. Specifically, thesecond conductive layer 148 is disposed in the form of strips in eachseparate pixel row in each of the plurality of pixel groups 111.Therefore, each pixel 110 includes an area covered with the secondconductive layer 148 and an area not covered with the second conductivelayer 148. The second conductive layer 148 can be made of the samematerial as the aforementioned first conductive layer 150.Alternatively, such a combination is possible, for example, that thefirst conductive layer 150 is made of a transparent electrode materialand the second conductive layer 148 is made of a light-blockingmaterial.

The second inorganic insulating layer 156 is provided above the secondconductive layer 148 across the plurality of pixels 110. Note here that,as mentioned above, the second conductive layer 148 is disposed in theform of strips in each separate pixel row in each of the plurality ofpixel groups 111. Therefore, each of the plurality of pixels 110includes an area where the second conducive layer 148 is sandwichedbetween the first inorganic insulating layer 154 and the secondinorganic insulating layer 156 and an area where the second conducivelayer 148 is not sandwiched between the first inorganic insulating layer154 and the second inorganic insulating layer 156.

The area where the second conducive layer 148 is not sandwiched betweenthe first inorganic insulating layer 154 and the second inorganicinsulating layer 156, i.e. the area of the slit provided in the secondconductive layer 148, is provided with a second contact hole 170 and athird contact hole 172. The second contact hole 170 and the thirdcontact hole 172 are both bored through the second inorganic insulatinglayer 156 and the first inorganic insulating layer 154. The secondcontact hole 170 reaches the first conductive layer 150. The thirdcontact hole 172 reaches the first metal layer 144. The second contacthole 170 and the third contact hole 172 are substantially equal indiameter to each other. The phrase “substantially equal” specificallymeans that the difference in diameter between the second contact hole170 and the third contact hole 172 ranges from −5% to 5%.

Note here that, in the present embodiment, the first contact hole 168 isdifferent in position from the second contact hole 170 in each of theplurality of pixels 110. That is, there is no overlapping area betweenan area where the first contact hole 168 is bored at the drain of theswitching element 136 and an area where the second contact hole 170 isbored at the first conductive layer 150.

It should be noted that the first contact hole 168 and the secondcontact hole 170 may be disposed in overlapping positions. For example,in a plan view, the area where the first contact hole 168 is bored atthe drain of the switching element 136 may be formed to include the areawhere the second contact hole 170 is bored at the first conductive layer150.

The area where the second conductive layer 148 is sandwiched between thefirst inorganic insulating layer 154 and the second inorganic insulatinglayer 156 is provided with a fourth contact hole 174. The fourth contacthole 174 is bored through the second inorganic insulating layer 156 andreaches the second conductive layer 148.

Note here that, as illustrated in FIG. 6, the fourth contact hole 174may be larger in diameter than the third contact hole 172 and the secondcontact hole 170.

The second inorganic insulating layer 156 can be made, for example, ofthe same material as the aforementioned first inorganic insulating layer154.

The third conductive layer 146 is a layer that functions as the pixelelectrodes 120 in the display mode. The third conductive layer 146 isprovided above the second inorganic insulating layer 156 in each of theplurality of pixels 110. Furthermore, the third conductive layer 146 isconnected to the first conductive layer 150 via the second contact hole170. The third conductive layer 146 has a slit 146 a in each of theplurality of pixels 110. It should be noted that, in the presentembodiment, the third conductive layer 146 is smaller than the firstconductive layer 150. Further, while the first conductive layer 150 hasno slit formed therein, the third conductive layer 150 has a slit 146 aformed therein. Although FIG. 6 illustrates only one slit 146a, theremay be two or more slits.

The third conductive layer 146 can be made of the same material as theaforementioned second conductive layer 148 or first conductive layer150. Alternatively, the structure of the second conductive layer 148 andthe third conductive layer 146 may be such a combined structure that thesecond conductive layer 148 is made of a light-blocking metal materialand the third conductive layer 146 serves as a transparent electrode.

The fourth conductive layer 152 is provided above the second inorganicinsulating layer 156 in each of the plurality of pixel groups 111. Morespecifically, a plurality of the fourth conductive layers 152 areprovided in the plurality of pixel groups 111. Furthermore, the fourthconductive layer 152 is connected to any of a plurality of the firstmetal layers 144 via a third contact hole 172 and connected to thesecond conductive layer 148 via the fourth contact hole 174. That is,the second conductive layer 148 is connected to the first metal layer144 via the fourth conductive layer 152.

As mentioned above, the second conductive layer 148 is a layer thatfunctions as the touch detection electrodes 135 in the touch drive mode.Meanwhile, the first metal layer 144 is a layer that functions as thetouch signal lines 127 in the touch drive mode. Therefore, by havingsuch a configuration as that described above, the touch detectionelectrodes 135 can be connected to the touch signal lines 127 via thefourth conductive layer 152.

As will be mentioned in detail later, the fourth conductive layer 152can be formed by the same photolithography step as the third conductivelayer 146 in the manufacturing process. Therefore, the fourth conductivelayer 152 can be made of the same material as the aforementioned thirdconductive layer 146.

Disposed above the third conductive layer 146 and the fourth conductivelayer 152 is an alignment film 164. The alignment film 164 is providedto cause liquid crystal molecules of the liquid crystal layer 158 toalign themselves in a predetermined direction.

The second substrate 108 is provided on the upper surface of the displayarea 104 a so as to face the first substrate 104. Disposed on thesurface of the second substrate 108 that faces the first substrate 104are a color filter 160, a light-blocking layer 162, and an alignmentfilm 166. The color filter 160 is provided in places facing eachseparate pixel 110. The light-blocking layer 162 (also called “blackmatrix”) is disposed in places demarcating each separate pixel 110. Thealignment film 166 is provided to cause the liquid crystal molecules ofthe liquid crystal layer 158 to align themselves in a predetermineddirection. The second substrate 108 may be similar to the firstsubstrate 104. The liquid crystal layer 158 is sandwiched between thefirst substrate 104 and the second substrate 108.

The foregoing has described a configuration of a pixel 110 of thedisplay device 100 according to the present embodiment. The followingdescribes a method for manufacturing a display device 100 according tothe present embodiment with reference to the drawings.

[Manufacturing Method]

FIGS. 12A to 20B are cross-sectional views illustrating a method formanufacturing a display device 100 according to the present embodiment.These drawings correspond a cross-section taken along line A1-A2 orB1-B2 of FIG. 6. The method for manufacturing a display device 100according to the present embodiment includes the following steps. Thefollowing describes a method for manufacturing an array substrate sideof a display device 100.

First, a plurality of switching elements 136, a plurality of scanningsignal lines 122, and a plurality of video signal lines 124 are formedover a first substrate 104 (FIGS. 12A and 12B). Each of the switchingelements 136 is provided in the corresponding one of a plurality ofpixels 110. In the present embodiment, the plurality of switchingelements 136 are thin-film transistors. The plurality of scanning signallines 122 are wires for selecting, in sequence, a plurality of pixelrows to which video signals are supplied. The plurality of video signallines 124 are wires for supplying video signals to the plurality ofpixels 110.

A first organic insulating layer 142 that covers the plurality of videosignal lines 124 is formed. The first organic insulating layer 142 canbe made of a material such as polyimide resin, acrylic resin, or acombination thereof. The first organic insulating layer 142 can beformed by a method such as a coating method.

Next, in each of the plurality of pixels 110, a first contact hole 168that reaches the source or drain of a switching element 136 of the pixel110 is formed (FIGS. 13A and 13B). In the present embodiment, a firstcontact hole 168 is formed in the first organic insulating layer 142 bya photolithography step so as to reach the drain of a switching element136 provided in each of the plurality of pixels 110.

Next, a first metal layer 144 that extends along any of the plurality ofvideo signal lines 124 is formed above the first organic insulatinglayer 142 (FIGS. 14A and 14B).

The first metal layer 144 can be made of a material having a laminatedstructure in which a W layer, a MoW layer, and an Al layer aresandwiched between upper and lower Mo layers, a laminated structure inwhich an Al layer is sandwiched between upper and lower Ti layers, orthe like. The first metal layer 144 can be formed by a method such as asputtering method. In one example, the three types of wires, namely thescanning signal lines 122, the video signal lines 124, and the firstmetal layer 144 are made of different metal materials, namely MoW, amaterial having a laminated structure in which an Al layer is sandwichedbetween upper and lower Ti layers, and a material having a laminatedstructure in which an Al layer is sandwiched between upper and lower Molayers, respectively.

Next, a first conductive layer 150 is formed above the first organicinsulating layer 142 in each of the plurality of pixels 110 (FIGS. 15Aand 15B). Note here that the first conductive layer 150 is formed so asto be separate from the first metal layer 144. This allows the firstconductive layer 150 to be connected to the switching elements 136 ofthe pixels 110 via the first contact holes 168.

The first conductive layer 150 can be made of a material such as ITO(indium tin oxide) or IZO (indium zinc oxide) or of any combinationthereof. The first conductive layer 150 can be formed by a method suchas a sputtering method. Further, instead of being made of a transparentelectrode material, the first conductive layer 150 can be made of thesame material as the first metal layer 144. In a case where the firstconductive layer 150 can be made of the same material as the first metallayer 144, the first conductive layer 150 and the first metal layer 144can be collectively manufactured through the same manufacturing processsteps.

Next, a first inorganic insulating layer 154 that covers the first metallayer 144 and the first conductive layer 150 is formed (FIGS. 16A and16B). The first inorganic insulating layer 154 can be made of a materialsuch as silicon oxide, silicon nitride, or a combination thereof. Thefirst inorganic insulating layer 154 can be formed by a method such as aCVD method or a sputtering method.

Next, a second conductive layer 148 is formed above the first inorganicinsulating layer 154 in each of a plurality of pixel groups 111 (FIGS.17A and 17B). In the present embodiment, as mentioned above, the firstconductive layer 150 is disposed in the form of strips in each separatepixel row in each of the plurality of pixel groups 111. Therefore, eachpixel 110 includes an area covered with the second conductive layer 148and an area not covered with the second conductive layer 148.

Next, a second inorganic insulating layer 156 that covers the pluralityof pixels 110 is formed above the second conductive layer 148 (FIGS. 18Aand 18B). The second inorganic insulating layer 156 may be made of thesame material and formed by the same method as the aforementioned firstinorganic insulating layer 154.

Next, in each of the plurality of pixels 110, a second contact hole 170that reaches the second conductive layer 148 is formed. Furthermore,along with the formation of the second contact hole 170, a third contacthole 172 that reaches the first metal layer 144 and a fourth contacthole 174 that reaches the second conductive layer 148 are formed in eachof the plurality of pixel groups 111 (see FIGS. 19A and 19B). That is,the second contact hole 170 and the third contact hole 172 are bothbored through the first inorganic insulating layer 154 and the secondinorganic insulation layer 156. Meanwhile, the fourth contact hole 174is bored through only the second inorganic insulating layer 156.

Note here that a third conductive layer 146 functions as an etchingstopper for the formation of the second contact hole 170, that the firstmetal layer 144 functions as an etching stopper for the formation of thethird contact hole 172, and that the second conductive layer 148functions as an etching stopper for the formation of the fourth contacthole 174. Therefore, the second contact hole 170, the third contact hole172, and the fourth contact hole 174, which are bored through differentlayered structures as mentioned above, can be simultaneously formed in asingle photolithography step. Further, since the second conductive layer148 functions as an etching stopper, the diameter of the fourth contacthole 174 in the second inorganic insulating layer 156 is comparativelylarger than the diameter of the second contact hole 170 and the diameterof the third contact hole 172. Further, since the first organicinsulating layer 142 is a thicker film than the first inorganicinsulating layer 154 and the second inorganic insulating layer 156, thediameter of the first contact hole 168 is comparatively larger than thediameters of the other contact holes (170, 172, and 174). The secondcontact hole 170 and the third contact hole 172, which are formed underthe same conditions, are substantially equal in diameter to each other.

Note here that the area of the first contact hole 168 is an area wherethe first organic insulating layer 142 has an opening for the drain ofthe switching element 136 and where the drain of the switching element136 and the first conductive layer 150 make contact with each other.Further, the area of the second contact hole 170 is an area where thefirst inorganic insulating layer 154 has an opening for the firstconductive layer 150 and where the third conductive layer 146 and thefirst conductive layer 150 make contact with each other. Further, thearea of the third contact hole 172 is an area where the first inorganicinsulating layer 154 has an opening for the first metal layer 144 andwhere the third conductive layer 146 and the first metal layer 144 makecontact with each other. Further, the area of the forth contact hole 174is an area where the second inorganic insulating layer 156 has anopening for the second conductive layer 148 and where a fourthconductive layer 152 and the second conductive layer 148 make contactwith each other.

Next, a third conductive layer 146 connected to the first conductivelayer 150 via the second contact hole 170 is formed above the secondinorganic insulating layer 156 in each of the plurality of pixels 110(FIGS. 20A and 20B). Next, a fourth conductive layer 152 connected tothe first metal layer 144 via the third contact hole 172 and connectedto the second conductive layer 148 via the fourth contact hole 174 isformed in each of the plurality of pixel groups 111 by aphotolithography step so as to be separate from the third conductivelayer 146 (FIGS. 21A and 21B).

The fourth conductive layer 152 is provided above the second inorganicinsulating layer 156 in each of the plurality of pixel groups 111.Furthermore, the fourth conductive layer 152 is connected to any of aplurality of the first metal layers 144 via a third contact hole 172 andconnected to the second conductive layer 148 via the fourth contact hole174. That is, the second conductive layer 148 is connected to the firstmetal layer 144 via the fourth conductive layer 152. The fourthconductive layer 152 is rectangular in the present embodiment, and thefourth conductive layer 152, the fourth contact hole 174, and the thirdcontact hole 172 overlap a light-blocking layer of a counter substrate.

As mentioned above, the second conductive layer 148 is a layer thatfunctions as the touch detection electrodes 135 in the touch drive mode.Further, the first metal layer 144 is a layer that functions as thetouch signal lines 127 in the touch drive mode. Therefore, such amanufacturing method as that described above makes it possible toconnect the touch detection electrodes 135 and the touch signal lines127 to each other via the fourth conductive layer 152.

A case is under consideration here where, as has been conventionallydone, the second conductive layer 148 (common electrodes 134 or touchdetection electrodes 135) is directly connected to the first metal layer144 (common potential lines 126 or touch signal lines 127) instead ofbeing connected to the first metal layer 144 (common potential lines 126or touch signal lines 127) via the fourth conductive layer 152 as in thecase of the present embodiment. In such a case, there is a need for astep in which a contact hole that reaches the first metal layer 144 isformed in the first inorganic insulating layer 154 after the formationof the first inorganic insulating layer 154 and before the formation ofthe second conductive layer 148. The subsequent formation of the secondconductive layer 148 causes the second conductive layer 148 to beconnected to the first metal layer 144 via the contact hole.

A manufacturing method such as that according to the present embodimentmakes it possible to omit the aforementioned step, thus making itpossible to suppress the rise in the number of masks needed and suppressthe rise in the number of photolithography steps.

The foregoing has described a method for manufacturing a display device100 according to the present embodiment. The method for manufacturing adisplay device 100 according to the present embodiment makes it possibleto suppress the rise in the number of masks needed and suppress the risein the number of photolithography steps.

While embodiments of the present invention have been described above,the present invention is not limited to the embodiments described abovebut may be applied in many variations without departing from the spiritof the present invention, and it is needless to say that such variationsare encompassed in the scope of the present invention.

What is claimed is:
 1. A display device comprising: A plurality ofpixels arranged in a matrix; a first video signal line supplying videosignals to a first pixel of the plurality of pixels; a first organicinsulating layer covering the first video signal line; a first touchsignal line provided on the first organic insulating layer so as toextend along the first video signal line; a first relay electrodeprovided on the first organic insulating layer in the first pixel andconnected to a first switching element of the first pixel via a firstcontact hole formed in the first organic insulating layer; a firstinorganic insulating layer covering the first relay electrode and thefirst touch signal line; a first touch detection electrode provided onthe first inorganic insulating layer in a pixel group including thefirst pixel, and electrically connected to the first touch signal line;a second inorganic insulating layer provided on the first touchdetection electrode; a first pixel electrode provided on the secondinorganic insulating layer in the first pixel and connected to the firstrelay electrode via a second contact hole formed in the first inorganicinsulating layer and the second inorganic insulating layer; and a secondrelay electrode provided on the second inorganic insulating layer,wherein the second relay electrode overlaps with first video signal lineand the first touch signal line, a first part of the second relayelectrode is connected to the first touch signal line via a thirdcontact hole formed in the first inorganic insulating film and thesecond inorganic insulating film, and a second part of the second relayelectrode is connected to the first touch detection electrode via afourth contact hole formed in the second inorganic insulating film. 2.The display device according to claim 1, further comprising a secondtouch detection electrode between the first inorganic insulating layerand the second inorganic insulating layer, wherein the second touchdetection electrode is adjacent to the first detection electrode with aslit, and the third contact hole is located in an area where the slit isformed.
 3. The display device according to claim 2, wherein the firstrelay electrode, the first to second touch detection electrodes, thefirst pixel electrode, and the second relay electrode serve astransparent electrodes.
 4. The display device according to claim 2,wherein the first touch signal line and the first relay electrode aremade of a light-blocking metal material.
 5. The display device accordingto claim 1, wherein the first contact hole is different in position fromthe second contact hole in the first pixel.
 6. The display deviceaccording to claim 3, wherein the first pixel electrode has a slit inthe first pixel.
 7. The display device according to claim 5, wherein thefourth contact hole is larger in diameter than the third contact hole.8. The display device according to claim 2, wherein the second relayelectrode is rectangular, and the second relay electrode, the fourthcontact hole, and the third contact hole overlap a light-blocking layerdisposed on a counter substrate, and the second relay electrode, thefourth contact hole and the third contact hole overlap with the firstvideo signal line.
 9. The display device according to claim 1, whereinin a plan view, the first contact hole is larger in diameter than thefourth contact hole and the second contact hole and the third contacthole are substantially equal in diameter to each other.
 10. A method formanufacturing a display device, comprising: forming a plurality of videosignal lines supplying video signals to a plurality of pixels; forming afirst organic insulating layer covering the plurality of video signallines; forming, in each of the plurality of pixels, a first contact holereaching a switching element of the pixel; forming, on the first organicinsulating layer, a first metal layer extending along any of theplurality of video signal lines; forming, on the first organicinsulating layer in each of the plurality of pixels, a first conductivelayer connected to a switching element of the pixel via the firstcontact hole; forming a first inorganic insulating layer covering thefirst metal layer and the first conductive layer; forming a secondconductive layer on the first inorganic insulating layer in each of aplurality of pixel groups; forming, on the second conductive layer, asecond inorganic insulating layer covering the plurality of pixels;forming, in each of the plurality of pixels, a second contact holereaching the first conductive layer and a third contact hole reachingthe first metal layer; forming a fourth contact hole reaching the secondconductive layer; forming, on the second inorganic insulating layer ineach of the plurality of pixels, a third conductive layer connected tothe first conductive layer via the second contact hole; forming, on thesecond inorganic insulating layer in each of the plurality of pixelgroups, a fourth conductive layer connected to the first metal layer viathe third contact hole and connected to the second conductive layer viathe fourth contact hole, and forming an alignment film directlycontacting the second inorganic insulating layer, the third conductivelayer and the fourth conductive layer.
 11. The method according to claim10, wherein the first contact hole is different in position from thesecond contact hole in each of the plurality of pixels.
 12. The methodaccording to claim 11, wherein the third conductive layer has a slit ineach of the plurality of pixels.
 13. The method according to claim 12,wherein the fourth contact hole is larger in diameter than the thirdcontact hole.
 14. The method according to claim 12, wherein in a planview, the first contact hole is larger in diameter than the fourthcontact hole and the second contact hole and the third contact hole aresubstantially equal in diameter to each other.
 15. A display devicecomprising: a plurality of pixels arranged in a matrix; a first videosignal line supplying video signals to a first pixel of the plurality ofpixels; a first organic insulating layer covering the first video signalline; a first common potential line provided on the first organicinsulating layer so as to extend along the first video signal line; afirst relay electrode provided on the first organic insulating layer inthe first pixel and connected to a first switching element of the firstpixel via a first contact hole formed in the first organic insulatinglayer; a first inorganic insulating layer covering the first relayelectrode and the first common potential line; a first common electrodeprovided on the first inorganic insulating layer in a pixel groupincluding the first pixel, and electrically connected to the firstcommon potential line; a second inorganic insulating layer provided onthe first common electrode; a first pixel electrode provided on thesecond inorganic insulating layer in the first pixel and connected tothe first relay electrode via a second contact hole formed in the firstinorganic insulating layer and the second inorganic insulating layer;and a second relay electrode provided on the second inorganic insulatinglayer, wherein the second relay electrode overlaps with the first videosignal line and the first common potential line, a first part of thesecond relay electrode is connected to the first common potential linevia a third contact hole formed in the first inorganic insulating filmand the second inorganic insulating film, and a second part of thesecond relay electrode is connected to the first common electrode via afourth contact hole formed in the second inorganic insulating film. 16.The display device according to claim 15, further comprising a secondcommon electrode between the first inorganic insulating layer and thesecond inorganic insulating layer, wherein the second common electrodeis adjacent to the first detection electrode with a slit, and the thirdcontact hole is located in an area where the slit is formed.
 17. Thedisplay device according to claim 16, wherein the first relay electrode,the first to second common electrodes, the first pixel electrode, andthe second relay electrode serve as transparent electrodes.
 18. Thedisplay device according to claim 16, wherein the first common potentialline and the first relay electrode are made of a light-blocking metalmaterial.
 19. The display device according to claim 15, wherein thefirst contact hole is different in position from the second contact holein the first pixel.
 20. The display device according to claim 19,wherein the second relay electrode is rectangular, and the second relayelectrode, the fourth contact hole, and the third contact hole overlap alight-blocking layer disposed on a counter substrate, and the secondrelay electrode, the fourth contact hole and the third contact holeoverlap with the first video signal line.